In tubular culverts, lining methods in which a pipe manufacturing apparatus that is self-propelled with a revolving motion is used to form a tubular body by spirally winding a continuously supplied elongated strip-like member that has joint parts formed on both side edge parts around the circumference of the forming frame of the pipe manufacturing apparatus, and engaging the joint parts that contact each other, after which this tubular body is left in place, and another tubular body is added by means of a strip-like member that is newly supplied to the front of this tubular body that has already been formed, have already been proposed, and are universally known.
Specifically, in the technique disclosed in Japanese Patent Application Laid-Open No. 8-261363, the forming frame is freely bendable, and can be applied not only to tubular culverts with a circular cross section, but also to tubular culverts with a rectangular cross section; furthermore, a flexible lining pipe can be molded so that the cross-sectional shape of this lining pipe conforms as closely as possible to the cross section of the tubular culvert. Furthermore, the technique disclosed in Japanese Patent Application Laid-Open No. 9-57850 is used on tubular culverts that have a circular cross section; in this technique, a small-diameter lining pipe is formed, and the diameter of this lining pipe is expanded so that a lining pipe is formed in conformity with the full cross section of the abovementioned circular tubular culvert.
However, in the case of the former technique (Japanese Patent Application Laid-Open No. 8-261363), it is difficult to cause the molded lining pipe to adhere tightly to the interior surface of the tubular culvert; as a result, the diameter of the lining pipe is somewhat smaller than the diameter of the tubular culvert, so that a cross-sectional loss cannot be avoided. Furthermore, in the case of the latter technique (Japanese Patent Application Laid-Open No. 9-57850), although it is certainly possible to form a lining pipe that conforms to the full cross section of the tubular culvert, an expansion operation must be performed each time, and it is not easy to feed in the strip-like member in a continuous operation, so that a bottleneck is created in the work.
Furthermore, in both of these prior-art techniques, a back-filling material such as a bonding cement or the like is injected into the space between the abovementioned lining pipe and the tubular culvert from the standpoint of reinforcement after the lining pipe has been inserted over a long distance. However, the gap between the lining pipe and the tubular culvert is small, so that this injection work involves difficulties. Consequently, the reliability in regard to the finishing [of the tubular culvert lining] is poor, and in the case of the abovementioned latter prior-art technique, such a back-filling operation must in fact be abandoned.
The present invention was devised in order to achieve a further development of the abovementioned prior-art techniques in which lining work is performed using a pipe manufacturing apparatus that is self-propelled with a revolving motion, and in order to find means of solving the problems of such techniques. It is a principal object of the present invention first of all to make it possible to cause the molded lining pipe to conform even more closely to the cross section of the tubular culvert, and secondly to facilitate the work of injecting the back-filling material and thus improve the reliability of such back-filling.